Vacuum controlled dampening device for secondary throttles



T. F. CRAMER 2,990,824 VACUUM CONTROLLED DAMPENING DEVICE FOR SECONDARY THROTTLES July 4, 1961 Filed Feb. 2. 1959 INVENTOR.

THOMAS F. CRAMER ATTORNEY VACUUM CONTROLLED DAMPENING DEVICE FOR SECONDARY THROTTLES Thomas F. Cramcr, Stratford, Ontario, Canada, assignor to Holley '(larbnretor Company, Van Dyke, Mich., a

corporation of Michigan Filed Feb. 2, 1959, Ser. No. 790,546 18 Claims. (Cl. 123.-103) The present invention relates to a dampening device in a multiple stage carburetion system effective to dampen or retard response of a secondary throttle under selected conditions.

A multiple stage carburetion system comprises an operator-controlled primary throttle plate assembly and a primary venturi vacuum controlled secondary throttle plate assembly which is operable to supply additional air flow to the combustion chambers at high speeds.

In engines having governing systems wherein at governed speed the primary throttle plate is automatically adjusted to restrict the fuel mixture to the combustion chambers, the subsequent movement of venturi-operated secondary plate is delayed and very quick, causing a compensating opening of the primary plate. The secondary plate in turn opens slightly due to the increased air flow through the primary venturi and repeated alternate adjustments or hunting of the primary and secondary plates result. This invention successfully prevents hunting by applying a dampening or resisting movement to the "secondary plate so that its initial closing after governing is modified and resultant changing of the primary throttle plate is substantially eliminated.

In general terms the dampening action is the result of connecting the secondary throttle actuator to a member constituting one wall of a chamber, substantially but not completely sealing the chamber with its interior at ambient pressure so that movement of said member in either direction is opposed by a yieldable force. A controlled leakage to the chamber permits response at a controlled rate.

It is therefore an object of the present invention to provide in a governed, multiple-stage carburetion system means for eliminating the hunting which occurs at .governed speeds.

It is a further object of the present invention to provide the secondary throttle plate assembly with means opposing exceptionally quick movement and subsequent hunting of the secondary throttle plate upon governed movement of the primary throttle plate.

It is a further object of the present invention to voppose exceptionally quick movement of the secondary throttle plate by connection thereof to a member constituting a movable Wall of a pressure chamber, substantially sealing the chamber with fluid pressure therein at ambient pressure, and providing a controlled leak to determine the rapidity of response of said secondary throttle plate.

It is a feature of the present invention to provide a chamber having a movable wall, a passage connecting said chamber to atmosphere, a valve controlling said passage, means responsive to primary venturi vacuum to control movement of a secondary throttle plate, means connecting said movable wall to the secondary throttle plate, means responsive to engine manifold vacuum controlling said valve, and means providing a controlled leak between said chamber and atmosphere.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawing, illustrating a preferred embodiment of the invention, wherein:

FIGURE 1 is a schematic partial bottom plan view of a four-barrel carburetor provided with a governor and secondary dampening device, looking in the direction of the arrows 1,1, FIGURE 2.

FIGURE 2 is a sectional View on the line 22, FIG- URE 1.

Referring now to the Figures, FIGURE 2 shows a four-barrel carburetor 10 having an air intake 12 sectioned as shown in FIGURE 1 to expose one of the primary barrels 14 and one of the secondary barrels 16. The primary barrels are provided with venturis 18 and include conventionally operated throttle plates 20 mounted on a shaft 22 extending across both primary barrels. The secondary barrels are provided with venturis 24 and throttle plates 26 mounted on shaft 28 which extends across both secondary barrels '16.

While a particular four-barrel carburetor is shown for purposes of illustration, it will be apparent that the invention is equally applicable to two-barrel or other multistage carburetors.

A vacuum device 30, commonly referred to as a governor diaphragm assembly, is mounted on the boss 32 extending from the carburetor throttle body 34. The assembly 30 includes a body 36 formed to provide re cesses 38 and 4G. The recess 40 is covered by a flexible diaphragm 42 which is secured to the body 36 by a cover member 44 formed to provide an air-tight chamber 46 of which the flexible diaphragm 42 forms a movable wall] The cover member may be secured by any suitable means such as screws 47.

As shown in FIGURE 2, the diaphragm 42 has secured to the center thereof a rod 48 passing through opening 50 in the body 36 and having a laterally extending end 52 pivotally secured to a lever 54 which is rigidly secured to the end of the primary throttle shaft 22 extending into the chamber 38. The shaft 22 is mounted in an anti-friction bearing 55, and a spring 56 is disposed between the bearing and washers 57 to provide a seal. A tension spring 58 attached between an adjustable pin 60 and a fiXcd Pin 64, secured to the lever 54, tends to hold the primary throttle plate 20 in the open position. An atmospherically vented cover plate 66 may be secured by screws 68 to housing 36, thereby protecting the mechanism within chamber 38.

Means are provided for connecting the interior of chamber 46 to variable pressures. An orifice 72 in the throat of primary venturi 18 and an orifice 74 below the primary throttle plate 20 are connected by passages 76 and 78 having fixed restrictions 80 and 82 respectively with passage 84 in the body member and passage 86 in the cover member 44 leading to chamber 46. A passage 88 connects passage 84 to a fitting 90.

Located at any desired position on the engine is a governor valve assembly 92 comprising a stationary house ing 94 adapted to be mounted on the engine and containing a shaft 96 driven in any suitable manner in proportion to engine or vehicle speed. Mounted for rotation with the shaft 96 is a laterally extending sleeve 98 having a spring 100 mounted within the axial passage 102 in the sleeve by attachment at one end to the internally threaded member 104, which is keyed in passage 102. Spring 1% is adjustable axially of sleeve 93 by turning the adjustment screw 106 which is reached by removing the access screw 108. The other end of the spring 100 is secured to the governor weight 110 movable radially of shaft 96 within the chamber 112 against the spring 100 and having at the free end thereof a valve 114 adapted to close the orifice 116 when the weight 110 is forced outwardly due to the rotation of the shaft 96 and the sleeve 98 in accordance with engine speed. The engine or vehicle speed at which the orifice 116 will be closed Pat nted July 4, 1961- is dependent, of course, upon the adjustment of the spring 100. It is apparent, also, that some other governor valve structure may be employed.

A vacuum balancing air bleed is provided through assembly 92 to chamber 46 when orifice 116 is uncovered. Conduit 118 between the air intake 12 of the carburetor and the housing 94 and conduit 120 between the housing 94 and the passage 88 in the body 36 are provided so that when the engine or vehicle is operating at a speed insufficient to close the orifice 116, engine vacuum will draw clean air through the conduit 118, into the housing 94, through the orifice 116 and into the chamber 112, through the passage 102 and an axial passage 122 in the shaft 96 and thence through the conduit 120 to the governor diaphragm assembly 30. When the engine reaches governed speed, the orifice 116 is closed and the air bleed through conduits 120 is cut ofl. When this occurs, vacuum in the chamber 46 urges the diaphragm 42 downwardly, as in FIGURE 2, against the spring 58 to close the primary throttle plates 20.

A secondary throttle diaphragm assembly 124 is mounted at the opposite side of the throttle body 34. This assembly comprises a body 126 having a recess 128 vented to the atmosphere through a plate 130 secured by screw 132 and a recess 134 closed by a flexible diaphragm 136 which is secured to the body 126 by means of a cover 138 formed to provide oppositely disposed chambers 140 and 142 between which the flexible diaphragm 136 forms a movable wall. The chamber 142 contains a compression spring 144 positioned between the cover 138 and diaphragm 136. A rod 146 is secured to the center of the diaphragm 136 so that the spring 144 urges the rod 146 upwardly to rotate a lever 148 secured rigidly to the secondary throttle shaft 28 in a direction to close the secondary throttle plates 26. A conduit 150 extending between the chamber 142 and the vacuum passages 151 and 152 opening into the throats of the primary and secondary venturis enables venturi vacuum to evacuate the chamber 142 and displace the diaphragm 136 downwardly, as in FIGURE 2, against the spring 144 to open the secondary throttle 26. The force of the spring 144 is selected so that the secondary throttle plate 26 will be open at any predetermined venturi vacuum.

The structure described above, or its equivalents, is well known in the art, and proper governing action depends upon the particular closing of the throttle plates and 26 when the engine or vehicle has reached a predetermined governing speed so as to diministh or cut off the flow of motive fluid to the engine. However, in the case of dual carburetion as described above, the automatic closing of the secondary throttle plates 26 lags behind that of the primary throttle plates 20, particularly at governed engine speeds at which the secondary plates 26 are not fully open so that linkage (not shown) usually effective to positively close the secondary plates 26 with the primary plates 20 does not come into operation. While this is tolerable in the normal function of the dual carburetor, e.g., during acceleration, it is highly objectionable ctor the purposes of governing. This causes hunting, since the primary throttle plates have to first close farther than would otherwise be required to compensate for the open secondary plates and then open when the secondary plates finally close.

In order to remedy this, means are provided to retard response of the secondary throttle plates under selected engine conditions. For this purpose chamber 140 is sealed by'a flexible boot 153, and provided with a passage 154. The cover 138 is provided with a passage 155 connected with the passage 154 and leading to atmosphere. If desired, passage 155 may,'like passage 118, be connected to the interior of the air flow passage of the carburetor below the air cleaner usually provided. Passage 155 is controlled by a valve 156 connected to flexible diaphragm 158 forming a chamber 160 with a recess in the cover 138. The valve 156 is not held tightly inguide 161 so that, when the opening therethrough is moved out of axial alignment with the passage 155, a restricted flow is permitted around the valve, thus performing a metering function. In some instances it might be of advantage to have an adjustable restriction bypassing the valve 156 so that the restricting action of both can complement each other. A compression spring 162 in the chamber biases valve 156 toward open position. A conduit 164 connects the interior of chamber 160 to a variable source of vacuum dependent on engine conditions. A desirable operation results when the conduit 164 is connected to the engine manifold, a portion of which is diagrammatically indicated at 166.

With the foregoing construction, when a predetermined speed below governed speed is reached, the primary venturi vacuum overcomes spring 144 and opens the second-' ary throttle plate 26. At this time, manifold vacuum is not sufficiently great to close valve 156. Accordingly, air within the chamber is not trapped and offers no resistance to movement of the diaphragm 136 in either direction.

However, when the speed increases to governed speed, bleed valve 114 closes and the combination of primary venturi and engine manifold vacuum move the primary throttle plate 20 toward closed position. This reduces primary venturi vacuum and increases engine manifold vacuum. The increase in engine manifold vacuum moves valve 156 toward closed position, thereby restricting the flow of air through passage 155. Thus, abrupt movement of diaphragm 136 in neither direction is opposed .and the force opposing movement of the diaphragm is yieldable and increases in magnitude in accordance with the amount of displacement. At the same time, air flow past the valve 156 permits a retarded movement of diaphragm 136.

As will be apparent from an inspection of FIGURE 2, the boot 153 may be omitted if the chambers 128 and 140 are sealed from atmosphere by blocking the vent provided in the plate 130.

In its broadest aspect, the dampening device disclosed herein is operable to provide a force opposing abrupt movement of a movable member from any intermediate position, the force being yieldable and of a magnitude which increases upon displacement of the member but which decreases with time.

I The drawing and the foregoing specification constitute a description of the improved vacuum controlled dampening device for secondary throttles in such full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What I claim as my invention is:

1. In an engine carburetor having a throttle plate, means responsive to an engine condition comprising a movable wall connected to said throttle plate to adjust its position, said responsive means being dependent on engine load and speed, a dampening device including a chamber partly formed by said movable wall, means providing a passage from said chamber to atmosphere, valve means operable to establish and interrupt substantially free communication between said chamber and atmosphere, and means responsive to an engine vacuum condition controlling said valve means.

2. In an engine carburetor having a throttle plate,

3. A multi-sta ge carburetor having primary and secondary passages including respectively primary" and secondary venturis and throttle plates therein, a speed responsive governor in control of said primary throttle, means responsive to venturi vacuum comprising a movable wall connected to said secondary throttle plate to adjust its position, a dampening device including a cham ber partly formed by said movable wall, and a restricted passage connecting the interior of said chamber to atmosphere.

4. A multi-stage carburetor having primary and secondary passages including respectively primary and secondary venturis and throttle plates therein, a speed responsive governor in control of said primary throttle, means responsive to venturi vacuum comprising a movable wall connected to said secondary throttle plate to adjust its position, a dampening device including a chamber partly formed by said movable wall, a passage conmeeting the interior of said chamber to atmosphere, and valve means operableto establish and interrupt substantially free communication between said chamber and atmosphere.

5. A multi-stage carburetor having primary and secondary passages including respectively primary and secondary venturis and throttle plates therein, a speed responsive governor in control of said primary throttle, means responsive to venturi vacuum comprising a movable wall connected to said secondary throttle plate to adjust its position, a dampening device including a chamber partly formed by said movable wall, a passage connecting the interior of said chamber to. atmosphere, valve means operable to establish and interrupt substantially free communication between said chamber and atmosphere, and means responsive to engine manifold vacuum connected to said valve means to control said valve means.

6. A multi-stage carburetor comprising primary and secondary barrels having respectively primary and secondary venturis and throttle plates therein, a governor connected to said primary throttle plate, a chamber having a movable wall connected to said secondary throttle, a passage connecting said chamber to venturi vacuum, means enclosing said movable wall to form therewitha second chamber, and a restricted passage connecting said second chamber to atmosphere.

7. A multi-stage carburetor comprising primary and secondary barrels having respectively primary and secondary venturis and throttle plates therein, a governor connected to said primary throttle plate, a chamber having a movable wall connected to said secondary throttle, a passage connecting said chamber to venturi vacuum, means enclosing said movable wall to form therewith a second chamber, a passage connecting said second chamber to atmosphere, and valve means selectively operable to establish and interrupt communication between the interior of said second chamber and atmosphere.

8. A multi-stage carburetor com-prising primary and secondary barrels having respectively primary and secondary venturis and throttle plates therein, a governor connected to said primary throttle plate, a chamber having a movable wall connected to said secondary throttle, a passage connecting said chamber to venturi vacuum, means enclosing said movable wall to form therewith a second chamber, a passage connecting said second chamber to atmosphere, valve means selectively operable to establish and interrupt communication between the interior of said second chamber and atmosphere, and means responsive to engine manifold vacuum connected to said valve means.

9. A multi-stage carburetor comprising primary and secondary barrels having respectively primary and secondary venturis and throttle plates therein, a governor connected to said primary throttle plate, a chamber havmeans enclosing said movable wall to form therewith a second chamber, a passage connecting said second chamber to atmosphere, valve means selectively operable to establish and interrupt communication between the interior of said second chamber and atmosphere, and means responsive to engine manifold vacuum connected to said valve means and effective to close said valve means upon an increase in manifold vacuum following movement of said primary throttle plate toward closedpo-sition by operation of said governor.

10. In an engine having a movable throttle control member, actuating means for controlling the position of said control member, said actuating means being responsive to an engine condition which is a function of engine load and speed and including a chamber having a movable wall connected to said control member, means providing a slow leakage of air between the interior of said chamber and atmosphere, and valve means responsive to variations inengine vacuum for regulating the movement of said wall in response to changes in venturi vacuum in the throttle closing direction.

11. A m-ulti-stage carburetor for an internal combustion engine, comprising a body, primary and secondary induction passages formed through said body, primary and secondary venturis formed respectively within said induction passages, primary and secondary throttle valves located respectively within said induction passages and adapted to control the flow of combustible mixtures therefrom to the intake manifold of said engine, means for manually controlling the position of said primary throttle valve, vacuum responsive means for controlling the position of said secondary throttle, said vacuum responsive means comprising a housing, a movable wall within said housing forming a first and second chamber therein, first conduit means communicating between said first chamber and a source of primary venturi vacuum, second conduit means communicating between said second chamber and a source of atmospheric pressure, and valve means responsive to variations in engine vacuum for regulating the degree of communication between said second chamber and said source of atmospheric pressure as aiforded by said second conduit means.

12. A multi-stage carburetor for an internal combustion engine, comprising a body with primary and secondary induction passages therethrough and having respectively primary and secondary throttle valves therein controlling the fiow of combustible mixtures to said engine, a venturi formed within said primary induction passage, means for manually controlling the position of said primary throttle valve, vacuum responsive means for controlling the position of said secondary throttle valve, said vacuum responsive means comprising a housing having a movable wall therein operatively connected to said secondary throttle valve and adapted to form at least one chamber, conduit means communicating between a source of venturi vacuum and said chamber, and valve means responsive to variations in engine vacuum for regulating the rate of movement of said wall in response to changes in venturi vacuum in the throttle closing direction.

13. In an engine carburetor having a throttle plate, means responsive to an engine condition comprising a movable wall connected to said throttle plate to adjust its position, said responsive means being dependent on engine load and speed, a dampening device including a chamber partly formed by said movable wall, means providing a restricted passage from said chamber to atmosphere, valve means operable to establish and interrupt substantially free communication between said chamber and atmosphere, and means responsive to an engine vacuum condition for controlling said valve means.

14. A multi-stage carburetor for an internal combustion engine, comprising a body, primary and secondary induction passages formed through said body, primary and secondary venturis formed respectively within said induction passages, primary and secondary throttle valves located respectively within said induction passages and adapted to control the flow of combustible mixtures therefrom to the intake manifold of said engine, means for manually controlling the position of said primary throttle valve, vacuum responsive means for controlling the position of said secondary throttle valve, said vacuum responsive means comprising a housing, a movable wall within said housing forming a first and second chamber therein, conduit means communicating between said first chamber and a source of primary venturi vacuum, means providing a restricted passage from said second chamber to the atmosphere, and valve means operable to establish and interrupt substantially free communication between said second chamber and atmosphere, and means responsive to an engine vacuum condition for controlling said valve means.

15. A multi-stage carburetor defined in claim 14 wherein said last-named means is responsive to engine manifold vacuum for controlling said valve means.

16. A multi-stage carburetor defined in claim 14 wherein resilient means is provided in said first chamber for urging said movable wall ,in a direction to close the secondary throttle valve.

17. A multi-stage carburetor defined in claim 14 wherein said valve means includes a valve member having a passage therein, said valve member being connected to a flexible wall.

18. A multi-stage carburetor defined in claim 14 wherein said valve means includes a valve member connected to a diaphragm, said valve member having a valve passage therein, and resilient means biasing said diaphragm and valve member in a direction so as to move said valve passage to a position which permits unrestricted com- 15 munication between the second chamber and atmosphere.

References Cited in the file of this patent UNITED STATES PATENTS 2,367,606 Olson Jan. 16, 1945 2,431,816 Mallory Dec. 2, 1947 2,867,196 Francis Jan. 9, 1959 

